REXTAC™ APAO polymers are known to be useful in hot melt adhesive applications both alone and as blends with tackifiers and/or other polymers. Text from Huntsman Polymers' (part of Huntsman Corporation in Houston, Tex.) web-site of www.huntsman.com (as printed on Mar. 19, 2002) includes the statement that:
“REXtac® APAO polymers provide an excellent base for the manufacture of a wide variety of hot melt adhesive and sealant systems. The compatibility of these amorphous polyolefins with many solvents, tackifiers, waxes, and other polymers make them suitable for many adhesive applications in packaging, construction, medical, and personal care applications. The chemical resistance and moisture barrier properties of REXtac® APAO also make it the choice for many sealant formulations where these properties help solve difficult applications.”
Further, the Huntsman web-site discloses that RT 2730 and RT 2725 are both butene-1 copolymers and are useful in hot melt adhesive applications. Nothing in the web-site however discloses that specific hydrocarbon resins or blends with other polymers can improve adhesive performance.
Other references have disclosed other amorphous polymers useful in adhesive applications. Examples include EP 442 045 (A2), which discloses sprayable hot melt adhesives of amorphous polyalphaolefins having 3 to 75 weight % C4 to C10 alpha-olefin, 25 to 95 weight % propylene and 0 to 20 weight % ethylene; and WO 00/146277 and WO 00/46278, which disclose metallocene based polyalphaolefin inter-polymers and adhesives thereof.
In addition, REXTAC™ APAO polymers are known to be useful in hot melt adhesive applications both alone and as blends with other polymers.
U.S. Pat. No. 5,468,807 discloses blends of REXTAC 2780 with POLYPROPYLENE RF355B having an MFR of 2.7. However, this reference does not disclose that polypropylene having a viscosity of 1500 mPa.s or less at 190° C. can be used successfully in an adhesive composition.
Other references of interest include U.S. Pat. Nos. 6,156,856; 6,160,071; 4,642,269; 5,854,354; 6,084,048; 4,950,720; 5,468,807; 6,180,229; 6,114,261; and 6,121,401; and European Patent Nos. EP 622380(B1), EP 769505 (B1) and EP 685495(B13).